CW is not just another mode like SSB, FM, PSK-31, etc.
It is a unique mode that has alot of advantages.
Consider the following.............
1. It a Universal Language
No matter who you are talking to in the world, you can complete a contact on CW. You cant say that about any other mode. Take for example, SSB. How can you talk to someone who does not understand a word of English? For example, what about a five and nine signal report? There are as many variations of "five and nine" as there are languages. Unless you and the other station can understand the numbers of a common language, you are at a full stop.
On CW, you can send "599". Regardless of what language the other station understands, "599" means the same in every language when sent by CW.
While the example that I have used above is about signal reports, it holds true for other parts of the QSO as well. Some countries use different phonetics so even getting your callsign can be a problem. On CW, no problem.
CW really is a Universal Language.
2. It needs very simple equipment.
There are plenty parts of the world where the cost of a commercial rig is prohibitive. The most simple transmitter to build is a CW transmitter. All you have to do is to generate a carrier and to turn it on and off. What could be more easy!!!
As a result, you will find stations on CW that you will never hear on any other mode. This is especially important if you are after DX.
3. Chasing DX.
Well if you into chasing DX on the HF/VHF bands, then you really do need to use CW if you want to work all the good DX on the bands. Needless to say, you will work plenty on SSB. But, there are times when the DX station will only operate on CW or is so weak, that you can only work them on CW.
4. Signal to Noise Ratio
As you well know, if you ever listen to a weak signal, it is only a matter of time before QSB (fading) will take the signal down into the noise. On SSB, once the signal goes beyond a certain point, then thats it, you have no idea what the other station is saying. On CW, it really is amazing how far into the noise a signal can go and you can still copy it.
The same of course holds true for signals that are very weak to start with. On SSB, you may know that someone is there but you cant make it out. On CW, you can complete the contact.
In fact, a CW signal can have more than a 10 dB advantage over a SSB signal.
What does this mean?
Consider the following situation. You can just about work a CW station in the noise with 100 watts. The DX station is running 100 watts as well. To have a weak SSB contact, you would both have to run over a 1 Kilowatt each!!
Now, thats some advantage.
5. EMC / RFI Problems (ie. Radio, Telephone and TV Interference)
We live in a world where there are more and more consumer items like TV's, HI-FI's, Radios, Computers, etc appearing in households. Many of these items behave very poorly in strong RF fields. This is probably one area that effects most radio amateurs to some degree. For some, it will mean that they cannot operate at all.
For example, on a telephone, an interfering SSB signal can sound like a garbled voice. With CW with the same power level, you will hear a slight clicking sound. ie. For the same power level, CW will cause less interference than SSB.
Now consider the fact that you can also get alot of contacts by running lower power on CW and you can see that it can be an obvious solution to alot of interference problems.
An SSB signal will usually occupy about 2.5 KHz. An FM signal will take up about 10 KHz. A CW QSO can take place in a bandwidth of about 300 Hz. As a result, you can fit alot more QSO's into a given bandwidth with CW. This is especially important on some of the HF bands like 40 metres where there is only 60 KHz available for SSB contacts.
In addition, because you are only listening to a single tone in a narow bandwidth, it is alot easier to filter out QRM (Interference).
7. Smaller Antenna's
As alot of Radio Amateurs in urban areas know, it can be very difficult to put up any decent size of antenna. With all the recent bad publicity that MMDS and Mobile Phone masts have got, alot of people are paranoid about any type of antenna in their neighbourhood. As a result, for alot of radio amateurs, the most they can get up is a simple wire antenna or an indoor antenna. Running 100 watts on SSB in a urban area can cause alot of problems. Again, the solution is CW. Less interference and the ability to use lower power. CW can make the difference between getting on the air and operating or not getting on the air at all.